With frigid temperatures and dismal snowstorms, some people wish they could hibernate this time of year. They may imagine sleeping soundly, dreaming for months until the spring. Factually speaking, however, that’s not really hibernation. While it’s often seen as nothing more than an extended sleep, hibernation is actually a rather distinct phenomenon in biology. In fact, hibernation itself comes with its own varieties—all different from sleep—that help animals survive extreme weather, food shortages, and other environmental hardships.

Hibernation falls under a broader term, torpor, that describes periods of dormancy experienced by animals. Torpor differs from sleep in that metabolism slows drastically to preserve energy. This can impact different animals in unique ways. Some reptiles, for example, slow their metabolism so dramatically that they stop breathing altogether, and the body temperature of an artic ground squirrel drops below freezing. In other cases, animals can still move around to occasionally eat or drink. Regardless of these specifics, torpor can be differentiated from sleep by brain activity: common sleep cycles aren’t experienced in torpor.

Dormancy: Is it Hibernation or Torpor or something else?

There are several differences between proper hibernation and torpor, but the biggest is time—torpor happens within a day while hibernation lasts anywhere from days to months. There are other states of dormancy to differentiate as well. Brumation, for example, is a type of dormancy for cold-blooded animals, and diapause is a similar experience that applies to insects. Each of these physiological processes fall under the same umbrella, and they can often be confused. Take the bear as an example. Because there isn’t a drastic drop in body temperature, the bear technically experiences periods of torpor instead of hibernation; still, others consider the bear a “light sleep hibernator” because the bear’s dormancy is a long-term state. Nevertheless, there’s no doubt that the bear’s experience is substantially different from sleep.

“Hibernation—along with all its variants—serves a unique purpose in the biological world…”

Doesn’t seem so simple now, does it? Hibernation—along with all its variants—serves a unique purpose in the biological world, a purpose with characteristics that differ by species, function, and circumstance. (Did you know that some animals actually go dormant in hotter months? It’s called estivation.) It’s not the month-long power nap many people take it to be. Think about that next time Groundhog Day rolls around.

Want to learn more about Hibernation?

Check out the sources for this post for more information:

• Sleep.org contrasts hibernation and sleep.
• The Forest Preserve District of Will County sheds light on the differences between hibernation and other states of dormancy.
• National Geographic, in addition to some fun facts, explains the reasoning behind why animals hibernate.
• Finally, for examples of different animals that experience periods of dormancy, visit the website of the Natural Park Service.